Many of Minnesota's state parks set aside sites for tent or RV camping in the winter, notably Mille Lacs Kathio State Park near Onamia and at Gooseberry Falls State Park north of Duluth, near Lake Superior. Maplewood State Park is located near Pelican Rapids and has year-round camping, including rustic cabins that are open year-round. The cabins have electricity but no running water.
Some of the state parks have information centers or museums that stay open all year where campers can use the flush toilets in the winter, warm up and get water for camping. While the parks have running water at the campsites during the summer season, they shut the water off once freezing temperatures arrive.
The state requires that the firewood you burn in its park be purchased locally to stop the spread of harmful diseases and insects. When camping in the winter, make sure you bring extra food. You will burn more calories in the cold than in the heat. Make sure you check the weather before you head out, as well. Blizzards and extremely cold weather are a hazard in Minnesota.